Bioinspired Bilayer Nanofibrous Membrane with Unidirectional Water Transport, Antimicrobial Properties, Antioxidant Capacity, and pH-Responsive Epigallocatechin Gallate Release

Significant challenges in wound care include excessive exudate, oxidative stress, and infection. Inspired by the cactus, a bilayer bionic nanofibrous membrane was fabricated via layer-by-layer electrospinning, consisting of a hydrophobic cellulose acetate butyrate (CAB) layer with grooved surfaces and a hydrophilic PAN/SPA layer loaded with epigallocatechin gallate (EGCG). The asymmetric wettability enabled rapid unidirectional liquid transport (<10 s), effectively managing wound exudates. EGCG incorporation imparted strong antioxidant capacity (DPPH scavenging >85%) and broad antibacterial activity, inhibiting >99% of <i>Staphylococcus aureus</i> and >84% of <i>Pseudomonas aeruginosa</i>. Moreover, pH-responsive release enabled adaptive drug delivery, with ∼80% release under infection-related alkaline conditions (pH 7-9) and ∼50% under acidic healing conditions (pH ∼ 6.5). In a full-thickness mouse skin defect model, the bilayer membrane significantly accelerated healing, minimized tissue adhesion, and achieved nearly complete closure (>99%) by day 12, with histological confirmation of superior re-epithelialization and epidermal regeneration. Collectively, this bilayer membrane integrates directional fluid management, antioxidant and antibacterial protection, and intelligent drug release, demonstrating potential as an advanced dressing for chronic wound care.